Although a world stripped of water and melted by temperatures hot enough to liquefy lead, Venus may once have been a planet much like Earth. The latest discoveries of the Venus Express craft show that the planets were very similar in the earlier days of the solar system. Permanently covered in clouds, Venus has approximately the same mass as the Earth. However, Venus was closer to the Sun and lacked a protective magnetic field.

The lack of a magnetic field made Venus vulnerable to water-stripping properties of the solar wind (a stream of electrically charged particles given out by the Sun). The carbon dioxide has been released into Venus atmosphere causing a runaway greenhouse effect. Due to hot temperatures registered on Venus, almost 457C by day and up to 240C by night, "the oceans boiled off and all the water ended up as water vapor in the atmosphere," said Hakan Svedhem, Venus Express team project scientist.

One key answer that scientists would still like to know is just how active the volcanoes of Venus are. "The contribution of volcanoes to the atmosphere could be enormous. Not knowing leaves a huge hole in our understanding of the climate," says Fred Taylor, a Venus Express interdisciplinary scientist.

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